Engine hesitates at steady throttle

Just fresh on this perfect site! My compliments to all.
Searched for a year, but eventually found my dream car.....a 456M GT in superb condition. Drives great, bought it via an official dealer including proper service and inspection at delivery. One issue they can't solve, and claim it's normal for every 456M. Hesitations when running with light steady throttle <2700rpm mainly 2nd and 3rd gear. Soon I touch the throttle for accel everything is smooth and fine (wrong words, should be GREAT). Anyhow, they changed sparkplugs, injectors, timebelts, diagnostic checks etc. Fill up with RON98, but doesn't help. Any suggestion?

 

This is not normal. It may be the gas. I don't know what RON98 is. Is that 98 octane? My M pulls strong straight through the power band and doesn't hesitate at all at any RPM. Being a handmade engine, every one is different though. Maybe they built yours on a friday after red wine hour.

 

My GranSport does that too on occassion....haven't figure dout why either. Usually low rev jusat poking along and th ecar seems to "pause" with the power delivery for 1/2 second sporadically.

 

Perhaps it is just me, but I don't quite understand 'hesitations'.

Are you saying there is a delay when you want to eccel in a light rpm and only in 2/3rd gear?

I've noticed a bit like this when warming up only. Not when after it has been running awhile.

 

If it is what I experience, when holding the throttle steady the power delivery is not steady...stuttering almost. Mine only happens rarely and usually if in first gear going relatively slowly....liek through a parkign lot. I attribute it to minor fluctuations in the power delivery but given the speed and gear it translates into a noticeable "fluctuation."

 

Do you mean hesitating when you press the throttle or slight on/off surging at steady throttle?

Not sure about the 456, but on my 348 this is a sign that one or more of my oxygen sensors has gone bad. I had some surging at steady throttle but it would disappear the moment I accelerated.

Kai

 

Hi, yes speaking about 'stuttering' when giving barely throttle, without accelerating. My experience is mainly referring to 2nd and 3rd gear but yes most likely it happens in 1st as well. The oxygen sensors might indeed be!

 

AND, all the time?

 

Hi,
The stuttering is very obvious at cold in 1st, 2 nd and 3rd gear (could accept that though), and with warm engine always when using the 2nd and 3rd gear with light throttle (less then 20%) up to 2700rpm. As soon as I accelerate by giving more throttle the stuttering dissappears, and also not present over 2700rpm light throttle.

 

Should not accept it. Although I've not driven a 456, the engine is very similar to my 550's and mine does nothing of the sort. Runs perfect from the word go, whatever the weather.

Welkom, overigens!


Onno

 

I'm not technically knowledgeable by any means - so I try to stay out of these types of threads - but I've had the same problem and it was the O2 sensor(s).

 

Congrats on the 456 Jan and welcome to FerrariChat!!

Just curious, did they check the sparkplug leads by any chance?

 

I had the same with my 456M GT. Problem disappeared completely after all valve guides had been replaced.
My car was consuming almost 1 litre of oil for every tank fill.
The stuttering was caused by the feedback signal from the cat, causing the fuel mixture goig up and down.

So Jan456, what is your oil consumption ?

Hans

 

Jan, welcome to the club.
You should not have any hesitation at all, at any rpm.
There are a couple of things you can try that are not expensive.
1- change the plugs with new set of NGK
2- change the relays that controls the O2 sensors (they are some $ 30.00 a piece) and can give you the same simptoms of bad O2 sensors even though your sensors are fine.
There is one on each side on top of the side engine compartment vent and you see them after you open the hood.

 

Jan,

Looking at your profile, I saw that you are living in the Netherlands, just like me.
Is your car dark green or dark blue.
Mine is blue pozzi.

Hans

 

Light throttle missfires are often as a result of fuelling faults e.g engine sensors (MAP/cam/crank/coolant temp/CO lambda or software issues), poor fuel or injectors, missfires under load/full throttle usually ignition related e.g spark plugs or leads. I'd start as someone mentioned above by replacing HT leads then get a diag check on the ferrari code reader with exhaust emmission and fuel pressure test if fault persists.

My 456 is crisp through the rev range and pulls smoothly from low revs in high gears - idles a bit fast though.

Jeremy

 

Thanks! Yes, the spark plugs were exchanged as well the injectors. Reading all the response, I shoot for the Oxygen sensors. Will give that a try.

 

Hi Hans,
thanks, no problems with oil consumption though. And the valve guides were already exchanged.

 

Hi Hans. Correct, living in Limburg. The 456 is dark green, with creme interior and original Dutch registrated. Looked for over a year cross Eu, and eventually found my dream car. Blue pozzi is like green marvolous.

 

Hi,
Thanks a lot! Will do these changes first.

 

.....exchanged to new Lambda sensors and new trigger relays. There was a lot of hope from both my self and the (official Ferrari) dealer that it would help. Particular as also the dealer recognized that the sympthoms are referring to Lambda sensors. A pity it didn't. The dealer tried also with new air-mass sensors, but didn't help either.....grrr..... The dealer is now suggesting to change the software slightly. Obviously they are capable to do that.... in fact overruling the Lambda sensors exactly at the critical rev's by making the mixture slightly richer or lean pending what helps. Claim this is done more often with the V12 in case of customer complaints.

 

Man, sounds like a PAIN in the ass!

Hope they sort it soon mate.

 

Hi I just noticed this thread. Your problem does not have anything to do with the o2 sensors. Since you are not getting any warning lights like the check engine lights which always come on with o2 or air mass sensor problems. My suggestion would be to change the spark plugs followed by HT leads. I had a similar problem in my mondial t and I was told it needed an engine rebuild! That didn't solve the problem but the leads did!

Btw the problem is not normal and should not be happening.

A

 

The plugs have been replaced mate.

Not too sure about the leads?? I asked him, but he replied saying the spark plugs were replaced. I asked him if they checked the leads.

CHECK THOSE LEADS JAN!

Engine rebuild on your Mondi? Spark plug leads fixed it? I HOPE you didnt take your Mondi back to the person that diagnosed that problem!

 

Thanks for the worries shared with me....... Yep, indeed the spark plugs are new since 1000km, and if you mean with leads the valve-leads.....yep they were changed from bronze to steel.
Any other help/smart ideas are welcome.......